Related Questions

If brushes of a D.C. generator are moved in order to bring these brushes in magnetic neutral axis, there will be
A Demagnetization only
B Cross magnetization as well as magnetization
C Cross-magnetization as well as demagnetizing
D Cross magnetization only
Electrical contact materials used in switches, brushes, relay must possess
A High thermal conductivity and high melting point
B Low thermal conductivity and low melting pointL
C High thermal conductivity and low melting point
D Low thermal conductivity and high melting point
Copper brushes in D.C. machine are used
A Where low voltage and high currents are involved
B Where high voltage and small currents are involved
C In both of the above cases
D In none of the above cases
In ________ the speed can be varied by changing the position of brushes.
A Slip ring motor
B Schrage motor
C Induction motor
D Repulsion motor
Array values are keyed by ______ values (called indexed arrays) or using ______ values (called associative arrays). Of course, these key methods can be combined as well.
A Float, string
B Positive number, negative number
C Even number, string
D String, Boolean
E Integer, string
In a D.C. generator in order to reduce sparking at brushes, the self-induced e.m.f. in the coil is neutralized by all of the following except
A Interpoles
B Dummy coils
C Compensating winding
D Shifting of axis of brushes
In D.C. generators, the brushes on commutator remain in contact with conductors which
A Lie under South Pole
B Lie under North Pole
C Lie under interpolar region
D Are farthest from the poles
_______ brushes are fragile and cause excessive wear of commutator,
A Natural graphite
B Hard carbon
C Electro graphitic
D Metal graphite
The rapid wear of brushes takes place due to
A Abrasion from dust
B Excessive spring pressure
C Rough commutator bars
D All of the above factors
To achieve sparkless commutation brushes of a D.C. generator are rockedm ahead so as to bring them
A Just ahead of magnetic neutral axis
B In magnetic neutral axis
C Just behind the magnetic neutral axis
D None of the above

Next steps